Breather tube. FRONT. PartQualifier: rear. rear. W/O GT3. A coolant Hose that feeds coolant back to the overflow or recovery bottle in a closed loop cooling system. HVAC Heater Hose. Breather tube. Connector tube. Cooler line. Engine Coolant Overflow. HVAC Heater. Inlet. Outlet. Reservoir. Return. Vent , Water TA.